1. Field
The present disclosure relates generally to a method and system for non-destructive inspection of components, and more particularly, to a method and system for automatic non-destructive inspection of turbine components using flash thermography.
2. Description of the Related Art
In many industrial applications, non-destructive testing methods are used to evaluate components without causing damage. One such application of non-destructive testing uses flash thermography to test components of a turbine engine such as a turbine blades or vanes, combustor baskets, or a transition component. These components frequently consist of a substrate coated with a thermal barrier coating that protects the substrate from high temperatures and a corrosive environment. For example, coated gas turbine components may require testing to determine the thickness of the thermal barrier coating or whether the coating has any delaminations, sections where the coated layer has become separated from the substrate. A delaminated layer may cause component failure during normal operation of the turbine.
Currently, inspection and testing of coated turbine components may be done using flash thermography, a commonly used non-destructive testing method in which the surface of the component is heated by a light pulse typically lasting only a few milliseconds. Under normal conditions, the part cools after flash heating, as the heat deposited at the surface flows toward the cooler interior. However, internal anomalies in the test piece, such as voids, inclusions, delamination, moisture, or changes in thickness or density, cause changes in the cooling rate at the surface. An infra-red camera is then used to capture infra-red radiation emitted by the component to form a thermographic image. The internal anomalies as referenced above would be visible in the thermographic image.
In order to capture images of the multitude of three dimensional surfaces of a component such that the images of the entire surface or nearly the entire surface are captured, a plurality of optical cameras, including perhaps a mixture of infrared and visible light cameras, are manually positioned around the coated surfaces of the component. The current method of imaging components using flash thermography involves a lengthy manual set up and positioning of the cameras relative to the component and the desired area of inspection. Two dimensional data is obtained from the images which are then correlated back to the three dimensional component. Having to manually set up the cameras for each required image requires a lot of time and manpower. Thus, an automatic inspection method reducing the time and manpower required for the current method of manually setting up a plurality of cameras for each required image of a component is desired.